BALTIMORE -- A pregnant Maryland teacher who was missing for more than a week has been found dead in a shallow grave, and her boyfriend is charged with her slaying, police said Wednesday.

Montgomery County police Chief Thomas Manger said at a news conference that investigators found the body of Laura Wallen in a shallow grave in Damascus, about 38 miles west of Washington on Wednesday. She was four months pregnant.

"We had a real sense of dread this is the way this was going to end up," Manger added.

Wallen's boyfriend, Tyler Tessier, was arrested Wednesday afternoon and charged with murder in her death. Police are waiting for autopsy results on the cause of death, and Manger said they don't know about a motive.

CBS affiliate WUSA-TV reports that police say Tessier made several visits to the area where Wallen's body was found. The station writes that once police started investigating, they found tire tracks that led to the location of Wallen's body.

Wallen's parents spoke at a news conference Monday and announced a $25,000 reward for information that led to her. Tessier sat with the parents, holding their hands, and cried through a brief statement.

Police had said early in the investigation that the last communications from Wallen were text messages to her family Monday. Those text messages were sent by Tessier from Wallen's phone, Manger said.

While Wallen was missing, Tessier was seen several times at the site where her body was found, police said. Detectives obtained a search warrant for the property, Manger said, and officers with cadaver dogs found the shallow grave.

Tessier will have a bail review hearing Thursday, Manger said. It could not be immediately determined if he has a lawyer.

A vigil was scheduled for Wallen on Wednesday night at Wilde Lake High School, but was canceled following the announcement of her murder, CBS Baltimore reports. Current and former students and members of the community had gathered in hopes of Wallen's safe return.

Once word spread that she'd been found dead and that her boyfriend had been arrested and charged with her murder, those able to speak were basically left at a loss for words.

"It's unreal. It's like one of them bad Lifetime movies that you just like 'yeah I know what's going to happen in the next five minutes of the movie,' like it's not real," former student Saquan Maxwell said. "Why? Like why? Like what motivated you, like why? Like how could you be so possessed with hate?"

"The community is devastated. Our heart goes out to the Wallen family," sad Rick Wilson of Wilde Lake High School.

"She influenced us to be better in life not just in school, in life," former student Hamad Wasti said.

"While all of our hearts are broken they know that their dear Laura is secure in the arms of God and they are holding onto the faith," family pastor Mark Hricko said.